The Roman god Janus gave the month of January its name and was associated with beginnings and transitions.
Janus was traditionally depicted with two faces, one looking forward and the other backward. This imagery made him an especially fitting symbol for the boundary between the old year and the new one. He was connected with doorways, gates, passages, entrances, and departures.
The Latin month name Ianuarius developed from Janus’s name. January became the first month in the Julian calendar, introduced by Julius Caesar in 45 BCE, although Roman calendar practices had changed over earlier periods. January 1 was not always universally observed as the start of the year in every historical culture.
Janus is distinct from Saturn, another important Roman deity associated with a December festival, Saturnalia. He also differs from the Greek god Hermes, whose roles included travel and messages. Modern New Year's symbolism often echoes Janus’s two-directional image without requiring a religious observance.